Subirrigation of Quercus rubra Seedlings: Nursery Stock Quality, Media Chemistry, and Early Field Performance

Abstract

Container seedling production systems for forest tree nurseries are challenged by the need for judicious water consumption. Subirrigation systems may provide an alternative to overhead systems by mitigating water use, yet remain relatively untested for propagation of forest tree seedlings. We evaluated effects of overhead versus subirrigation under varying media (40:60, 60:40, and 80:20 peat:perlite) and fertilization (0 or 1.2 g nitrogen/plant) regimes on nursery development and first-year field performance of northern red oak (Quercus rubra L.) seedlings. Fertilization increased aboveground biomass production and nutrient content, but decreased root dry weight. Relative to overhead-irrigated seedlings, subirrigation increased red oak seedling aboveground biomass production as well as above- and belowground nitrogen content under fertilized conditions. Media had no effect on plant response. Subirrigation increased electrical conductivity (5 dS·m−1 greater) and decreased pH in the upper media zone (0 to 5 cm from top), whereas the opposite effect was found in the lower zone. Nursery fertilization was associated with reduced field survival and growth, which may have been the result of transplant stress resulting from higher shoot:root. Subirrigated seedlings had greater field diameter growth. Our results suggest that subirrigation could serve as a viable alternative to overhead systems in container propagation of hardwood seedlings.